Yellow ink
The reason it won't print B/W if it's out of yellow ink is probably because of the forensic yellow dots code printed on each page, courtesy (we think) of the US Government. The pattern of yellow dots encrypts information like time and date and a serial number of the printer according to the EFF.
https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots
I wonder if printing a faint yellow background on each page would defeat this coding scheme?
Biting the hand that feeds IT
